The invention relates to an array substrate, a manufacturing method of the array substrate, and a liquid crystal display.
The Liquid crystal display (LCD) is an ultra-thin planar display apparatus. A liquid crystal panel generally constitutes of a color filter substrate and an array substrate, bonded together with a liquid crystal layer sealed in-between. The array substrate is also named thin film transistor (TFT) array substrate, comprising a substrate of a glass material. The substrate is provided with gate lines and data lines, crossing with each other. The adjacent gate lines and data lines define pixel regions, each comprising components such as a TFT device, a common electrode, and a pixel electrode.
As a liquid crystal molecular itself does not emit light, a LCD requires a light source for image displaying. A LCD can be categorized as a transmissive type, a reflective type, or a transreflective type, based on the way using the light source and the structure of the array substrate.
The transmissive type TFT-LCD employs a backlight as the light source, disposed behind the liquid crystal panel. The pixel electrode on the array substrate is a transparent electrode, used as a transparent region, amicable for light from the backlight to transmit through the liquid crystal layer to display images. The reflective type TFT-LCD employs a front light or an exterior light as the light source. A pixel electrode of metal or other materials with excellent reflective properties is disposed on the array substrate as a reflective region, suitable for reflecting the light from the front light or the exterior light. The transreflective type TFT-LCD can be deemed as a combination of the transmissive type LCD and the reflective type LCD, where both the reflective region and the transmissive region are disposed on the array substrate, and both the backlight and the exterior light are used for image displaying.
The transmissive type LCD has an advantage of being able to display a bright image in a dark environment; nevertheless, it has the disadvantage that only a low percentage of light from the backlight is transmitted, meaning a low utilization rate of the backlight. Improving the display luminance demands significantly raising the luminance of the backlight, necessitating high energy consumption. The reflective type LCD has the advantage of being able to use sun light or man-made light as the light source of LCD, and thus has relatively low energy consumption; it, however, can not display an image in a dark environment, due to the dependency on an exterior light.
The transreflective type LCD combines the structure of the transmissive type and the reflective type LCD, and thus can be used in either the transmissive or the reflective mode. FIG. 1 is a top view, showing the schematic configuration of one pixel region in a transreflective TFT-LCD, while FIG. 2 is a cross-sectional view taken from line A-A of FIG. 1. The manufacturing method for the transreflective TFT-LCD in prior art generally comprises steps of: first, forming, with a patterning process, a gate electrode 10, a gate line 2, a semiconductor layer 11 and a doped semiconductor layer 12, a source electrode 13, a drain electrode 14, and a data line 3 on a substrate 1, wherein, the source electrode 13 and the drain electrode 14 are located above and insulated from the gate electrode 10; forming a passivation layer 17 to cover the gate electrode 10, the source electrode 13, and the drain electrode 14; forming a though hole 15 that extends all the way through the passivation layer 17 above the source electrode 14 with a patterning process; forming a transmissive region electrode 61 at a position corresponding to a transmissive region 4 and above the passivation layer 17 with a patterning process; and forming a reflective region electrode 62 at the position corresponding to a reflective region 5 and on the passivation layer 17 with a patterning process.
In the process aforementioned, each patterning process comprises steps of forming a film, applying a photoresist layer, exposing, developing, etching, removing the photoresist, cleaning, and etc. In the manufacturing process of a TFT-LCD, each patterning process suffers the chance of micro contamination, which adversely influences the qualification ratio of the products. Further, each patterning process cost a large amount of time, labor, and equipment investment. Therefore, the transreflective liquid crystal display has the disadvantages of complex manufacturing procedures, low utilization rate, low qualification ratio, significant chance of contamination, and large amount of labor, time, and equipment investment.